Transparent composites and laminates and methods for making

ABSTRACT

An exemplary method for making a transparent composite includes steps of combining a refractive index modifier with a precursor solution, combining glass with the precursor solution, and curing the precursor solution to create a transparent glass reinforced polymer composite. An exemplary transparent composite comprises a glass reinforced thermosetting polymer composite layer sandwiched between glass layers.

STATEMENT OF GOVERNMENT INTEREST

This invention was made with Government assistance under NationalScience Foundation Grant No. NSF 0196428. The Government has certainrights in the invention.

FIELD OF THE INVENTION

A field of the invention is methods for making transparent compositesand laminates. Another field of the invention is transparent compositesand laminates.

BACKGROUND

Although glass is the most common transparent material used inbuildings, vehicles, and the like, glass is not acceptable for all suchapplications. Glass is relatively heavy and brittle, and may shatterinto a multiplicity of sharp parts when impacted. These properties makeglass disadvantageous for many applications, including some building andvehicle windows. Additionally, glass is difficult to form into complexshapes.

For many applications in which the potential for impact or other strainsand/or stresses exist, there exists a general need for mechanicallystrong composite materials that are of high optical quality and have anoptical transparency similar or equivalent to that of glass. Polymerssuch as polymethylmethacrylate (PMMA), sold under the trademarkPLEXIGLASS, are used in place of glass in certain applications in whichboth impact resistance and optical transparency are required.Unfortunately, thermoplastic polymers such as PMMA still do not havesufficient mechanical strength for many current applications.

One method of increasing the mechanical strength of polymers like PMMAis to reinforce them with strong glass fibers. This technology ispracticed in the manufacture of fiberglass-reinforced plastics (FRP). Inmost cases, however, the introduction of glass fibers into an opticallytransparent polymer limits or destroys the transparency of the polymer.Commercial FRP composites presently produced are either optically opaqueor translucent such that an object at distances greater than about a fewfeet cannot be clearly seen through them, and/or significant distortionsoccur.

Among the problems that exist in the aforesaid glass fiber/thermoplasticpolymer composites is that changes in the temperature of such compositescan cause the relative refractive indices of the glass fibers andpolymer to change relative to one another such that they becomemismatched. While the impact resistance of a thermoplastic polymer maybe better than that: of glass, its strength is lower. The stiffness ofthe thermoplastic polymer can also be undesirable for some applications.Finally, the thermoplastic polymer tends to degrade quickly withincreasing temperature. This mismatching results in degraded compositeclarity and/or transparency. This lack of clarity with temperaturechange means that glass fiber-reinforced transparent composites loseclarity when used in anything except for a narrow range of temperatures.Also, even within a limited temperature range, the clarity of glassfiber-reinforced composites may be noticeably less than that of glass.This is unacceptable for applications such as use for home or buildingwindows.

As a result of these and other problems, unresolved needs remain in theart.

SUMMARY OF THE INVENTION

An exemplary method for making a transparent composite includes steps ofcombining a refractive index modifier with a polymer precursor solution,combining glass with the precursor solution, and curing the precursorsolution to create a transparent glass reinforced polymer composite. Anexemplary laminate includes a glass reinforced thermosetting polymercomposite bound to glass layers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart illustrating exemplary steps of a method of theinvention;

FIG. 2 is a flowchart illustrating additional exemplary steps of amethod of the invention;

FIG. 3 is a schematic cross section of an exemplary laminate thatresults from practice of a method of the invention; and

FIG. 4 is a schematic cross section of a second exemplary laminate thatresults from practice of a method of the invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Before describing exemplary embodiments of the invention in detail, itwill be appreciated that the present invention includes transparentlaminates, transparent composites, and methods for making the same.Accordingly, it will be understood that in describing methods of theinvention for making transparent laminates and composites, descriptionis likewise being made of transparent composites and laminates of theinvention.

FIG. 1 is a flowchart illustrating steps of one exemplary method of theinvention. An exemplary method for making a transparent composite 10includes a step of empirically determining the amount of a refractiveindex modifier to add to a precursor solution to result in the precursorsolution having a desired refractive index when cured into a polymer(block 10). As used herein, the term “refractive index modifier” isintended to broadly refer to any material useful to modify therefractive index of a material, and the terms “precursor solution” and“polymer precursor solution” are intended to broadly refer to a solutioncapable of being polymerized. A precursor solution, for example, may bea solution containing a monomer, carrier or solvent, some polymer,un-saturated polymer, polymer dissolved in monomer solution, and/oradditional materials. A precursor solution may also be substantiallypure liquid monomer. It will be appreciated that the terms “polymerprecursor solution” and “precursor solution” may be used interchangeablyherein.

The polymer precursor solution preferably contains a monomer orun-saturated polymer that will be cured into a thermosetting polymer asopposed to material(s) that will polymerize into a thermoplasticpolymer. Thermosetting polymers are preferred since they have a greaterstrength and stiffness than thermoplastics and do not degrade withincreasing temperature as thermoplastics do. The polymer that resultsfrom curing is also transparent. Exemplary precursor solutions includeesters, ethylenes, acrylics, vinyls, epoxies, urethanes and mixtures ofthe same. One exemplary precursor that has proven useful in practice ofthe invention contains unsaturated polyester (—(CH₂═CHRCO)_(n)—),available commercially, for instance, from Ashland Chemical Co, Dublin,Ohio.

Exemplary refractive index modification is possible by adding apolymer(s) that has a higher or lower refractive index than thecandidate host polymer to respectively raise or lower its refractiveindex. The refractive index modifier should also be compatible with thehost polymer to prevent phase segregation or other effects that couldlead scattering of light in the resultant polymer. Another examplerefractive index modifier is any chemical(s) that alters thecrystallinity or density or the polarizable electrons per unit volume ofthe host polymer. Chemicals that increase these properties can be usedto increase the refractive index of the host polymer, and chemicals thatdecrease these properties can be used to decrease refractive index ofhost polymer.

Fluorinated polymers are examples of chemicals that increase refractiveindex, while chlorinated polymers are examples of chemicals thatdecrease the refractive index. When practicing the invention using aprecursor solution containing an ester monomer or unsaturated polymer,exemplary refractive index modifiers include divinyl benzene and ordi-butyl phthalate. Another exemplary refractive index modifier believedto be useful to raise the refractive index of polyester is apolycarbonate resin.

In addition to chemicals, it has been discovered that nanoparticles area suitable refractive index modifier for practice of the invention.Nanoparticles with a diameter that is less than that of visible light donot have a noticeable effect on the transmission of the visible lightthrough the transparent polymer. Visible light has a wavelength ofbetween about 400-700 nm. Accordingly, it is preferred thatnanoparticles used in methods of the invention as a refractive indexmodifier have a diameter of less than about 400 nm, and more preferablyof less than about 200 nm. Nanoparticles may also be desirable sincethey can be used to introduce other functionalities in addition toincreasing mechanical strength, such as reflecting short wavelengthultra-violet light. Substantially platelet shaped, cylindrical shaped,and other shaped nanoparticles may be used. Nanoparticles may be made ofmetal oxides such as titanium oxide and/or titanium dioxide, ceramics,in addition to other suitable materials.

Nanoparticles that have a refractive index greater than the host polymerwill increase the refractive index of the polymer, and vice versa. Byway of example, titanium dioxide nanoparticles have a refractive indexgreater than polyester. They may therefore be used in a method of theinvention as a refractive index modifier to increase the refractiveindex of a polyester that results from the curing of a polyesterprecursor solution. Nanoparticles used as refractive index modifiersshould also be selected to insure that other properties of the polymerare not adversely affected, with an example adverse effect being areaction with the polymer over time.

The step 10 of empirically determining the amount of the refractiveindex modifier, whether it be a chemical solution, nanoparticles, oranother modifier, to combine with the precursor solution may includedetermining a desired refractive index, adding a first amount ofmodifier to the precursor solution, curing the solution, and determiningthe refractive index of the polymer that results. This sequence of stepsmay then be repeated using a lesser or greater relative amount ofmodifier based on the result of the first iteration. After from a few toseveral iterations of this sequence, a suitable ratio of modifier can bedetermined that results in the refractive index of the final polymerhaving a desired value. By way of example, it is believed that betweenabout 0.5% to about 3% by weight (based on total weight of finalsolution) of titanium dioxide or other titanium nanoparticles may be auseful amount to add to a precursor solution that will cure to apolyester polymer.

The desired value of the refractive index is preferably substantiallyequal to the refractive index of the glass fibers that will be combinedwith the precursor solution. This refractive index may be determined byexperiment, or, more preferably, is obtained from literature. Forexample, a reported refractive index for E-glass fibers is 1.55, and forS-glass fibers is 1.52. It is preferred that the polymerized precursorsolution have a refractive index that substantially matches therefractive index of the glass fibers. This results in minimal to nonoticeable distortion when images are viewed through the finaltransparent glass reinforced polymer composite. Refractive indexes thatare at least within about 1% of one another are preferred, althoughindexes that are within about 2% of one another are believed to performsatisfactorily. Most preferably, the refractive index of the polymersubstantially equals that of the glass fibers, or is at least withinabout 0.5%. It is believed that refractive indexes that differ from oneanother by more than about 10% result in an unacceptable level ofdistortion.

In the exemplary method, a required amount of refractive index modifieris combined with the precursor solution so that the solution, when curedinto a polymer, has the desired refractive index (block 12). This mayoccur, for example, by combining divinyl benzene or polycarbonate resin,or titanium oxide/dioxide nanoparticles with the precursor solutionwhile the precursor solution is contained in a container such as a mold.Mixing may be provided to achieve suitable distribution.

The exemplary method next includes a step of depositing a glass fibersheet into the precursor solution in the container (block 14). The glassfiber sheet may include any suitable silica based glass fibers, withE-glass fibers, S-glass fibers, A-glass fibers, AF-glass fibers, C-glassfibers, being some examples. The fibers should be transparent and havegood tensile strength. S-glass is an example of a glass fiber thatoffers relatively high tensile strength. Although E-glass fibers haveslightly lower mechanical properties, they are typically commerciallyavailable at a significantly lower cost than S-glass fibers.

Substantially continuous fibers may be used, as well as shorter fibers.Fibers that are too short may result in a less than desirable mechanicalstrength. It is believed that fibers having a length of at least about50, and more preferably at least about 100 times their diameter providegood mechanical strength. In many applications substantially continuousfibers that have a length the same or greater than the size of thetransparent composite will prove beneficial. As used herein, the term“continuous fiber” when used in this context is intended to be broadlyinterpreted as having a length that is close to or greater than thelength of the composite being made. For example, when practicing amethod of the invention to make a transparent composite having a lengthof about 18″, fibers of about 18″ may prove useful. The fibers then maybe placed so that they run continuously across the length of thecomposite.

The fibers may be thick enough to provide a desired degree of strength,but not so thick that they are overly stiff and relatively brittle.Diameters of between about 10 and about 25 micrometers are believed tobe suitable, although practice of the invention using other diameters isalso contemplated. Nano-fibers may be useful. When the precursorsolution is contained in a container such as a mold, the fiber sheet maybe deposited onto the surface of the solution. Preferably substantiallyall of the fibers become wetted with the precursor solution.

The present invention contemplates use of glass fibers in forms otherthan sheets of fibers. Loose fibers may be used, for example, in avariety of diameters, lengths, orientations, and the like. Glass inother forms, including a substantially planar and flexible ribbon, isalso contemplated for use in addition to or as an alternative to glassfibers. For many applications, glass fibers will be preferred overribbon because fiber's three-dimensional orientation can be advantageousto contribute mechanical strength in multiple directions.

Glass is preferably provided, regardless of whether it be in fiber,ribbon or other form, in an amount so that the final volume ratio of theglass is between about 15-30%. Referring in particular to fiber, it isbelieved that a 50% maximum fiber volume ratio is a useful upper limitas above this fiber fraction the amount of polymer will be low which mayaffect bonding with the fibers and cause loss of transparency. Too lowof a fiber volume percentage may result in a final composite of limitedmechanical strength. It is believed that a minimum fiber volume ratio ofabout 10% is useful to achieve significant mechanical strengthadvantages of the fibers, although lower content is contemplated and maybe useful for some applications.

The amount of fiber, fiber length, fiber diameter, fiber orientation,and the fiber entanglement are variables that may be altered to affectthe strength and flexibility of the final glass reinforced polymercomposite. For example, the angle of orientation of fibers may be variedto alter the strength of the final composite in a particular direction.In some methods of the invention, entangled fibers are provided insheets with a generally random and equally distributed orientation. Inother methods of the invention, fibers may be provided in only the Xdirection, crossed in both the X and Y direction, and in other angularvariations as may be desirable for a particular application.

Some invention embodiments further include steps of coating the glassfibers with a coupling agent to enhance binding with the polymer thatwill result when the precursor solution is cured. For example, a silanecoupling agent may be coated on the glass fibers. Silane coupling agentsare known to improve the adhesion between glass fibers and polyester,for example. Silane coatings developed for glass fibers typically havean alkoxy moiety attached to the silica group that interacts well withglass to provide a hydrophobic bond, and a functionalized endgroup thatreacts with the polymer to form a covalent bond. Other suitable couplingand binding agents may be selected based on the polymer used and otherconsiderations.

The precursor solution with the glass fibers therein is then cured toresult in a transparent glass reinforced polymer composite (block 16).Curing may occur through polymerization by application of heat, achemical initiator and/or an accelerator. It may be desirable in someapplications to avoid the use of heat and pressure. In such cases,polymerization may be accomplished by addition of a chemical initiatorand allowing the reaction to occur at room temperature over a period oftime that may range from several hours up to a few days. By way ofexample, MEKP (methyl ethyl ketone peroxide), available commerciallyfrom Aldrich Chemical Co., may be added as an initiator when using anunsaturated polyester precursor solution. Those knowledgeable in the artwill appreciate that the amount of initiator required may be empiricallydetermined, or may be obtained by reference to literature. Whenpracticing the method using unsaturated polyester, for example, about1.2% by weight MEKP may be useful. Accelerators, such as cobalt octoateor cobalt napthanate, may also be added if desired to speed thereaction.

Polymerization results in the glass fibers being encapsulated and boundto the polymer. A transparent glass reinforced polymer composite resultsthat combines the transparency of glass, the flexibility of the polymerand a dramatically enhanced mechanical strength due to the presence ofthe glass fibers. The glass reinforced polymer composite preferably hassufficient flexibility so that it can withstand relatively high impactsconcentrated in small areas without breakage or shattering. These andother properties make composites made through methods of the inventionsuitable for a wide range of applications, with examples includingvehicle windshields, impact-proof or resistant transparent composites,hurricane glass, airplane and ship glass, portable electronics displayglass, and the like.

In other embodiments of the invention, subsequent steps may includemaking additional glass reinforced polymer composite layers through thesteps of FIG. 1 or other methods and combining these to form amulti-layer composite. The various glass reinforced polymer compositelayers may be prepared separately and bound together using a bindingagent or other method, or may be formed one on top of another. That is,a precursor solution may be deposited on the first glass reinforcedpolymer composite, mixed with a refractive index modifier, and a fibersheet deposited therein. This solution can then be cured to create asecond glass reinforced polymer composite layer overlying the first.

Different numbers of layers may be combined to suit differentapplications. Typical final composites may have varying thickness, with1-3 mm being exemplary, although other thicknesses are contemplated. Byway of particular example, a 7-9 layer composite may have a thickness ofabout 3 mm. Other thickness' are of course possible within practice ofthe invention, and may be desirable depending on application. It isnoted that any difference between polymer and glass fiber refractiveindexes will cause increasing light scattering with increasing layers,so the benefits of having closely matching refractive indexes areincreased with increasing layers.

Methods of the invention may include practicing steps of the inventionin a shaped mold so that the resulting transparent glass reinforcedpolymer composite has a desired shape. Desired shapes and finalcomposites may be, by way of example and not limitation, substantiallyflat plates; curved, arched, or otherwise shaped window panes; vehiclewindows such as curved windshields; and the like. The resultantcomposites may have substantially planar surfaces, or may even haveundulating surfaces as may be desired for particular applications.Methods of the invention may likewise include steps of cutting the glassreinforced polymer composite to achieve a desired shape, polishing thecomposite, and other post formation steps.

Other methods of the invention may include additional steps of binding aglass layer to a glass reinforced polymer composite made through stepsof an invention embodiment such as that illustrated in FIG. 1. FIG. 2 isa flow chart illustrating exemplary additional steps. It will beunderstood that the present invention includes the transparent laminatethat results from the steps of FIG. 2 in addition to other transparentlaminates. Referring now to FIG. 2, a coupling agent such as a silane isapplied to at least one surface of a glass reinforced polymer composite(block 30) that may be made, for example, through the steps of FIG. 1 oranother method of the invention. A glass layer is then bound to thesurface (block 32) to create a glass/glass reinforced polymer laminate.A coupling agent, with a silane being an example, may also be applied tothe glass layer surface. A glass layer may also be bound to an oppositesurface of the glass reinforced polymer composite to create a threelayer composite. FIG. 3 is a schematic cross-section of such a laminate,with the glass fiber composite layer 30 sandwiched between the glasslayers 32. Embodiments of the invention include the laminate of FIG. 3(and that of FIG. 4) as well as other transparent laminates made throughmethods of the invention.

The glass layers 32 are preferably selected to have a refractive indexthat closely matches (e.g., within about 2%), or is preferablysubstantially equal to, the refractive index of the glass fibers in theglass reinforced polymer composite layer 30. The binding agent appliedto the opposite surfaces of the glass reinforced polymer composite layer30 may be any that is suitable for use with a thermosetting polymer thatforms the layer 30, with silane coupling agents being one example. Useof this and other suitable binding agents in combination with use of thethermosetting polymer of the layer 30 allows the layers 30 and 32 to bebound at room temperature and pressure. Methods of the invention therebyrealize cost and effort savings in the production of laminates such asthose shown in FIGS. 3 and 4. The thicknesses of the layers 30 and 32may vary depending on application design considerations, with usefulranges believed to be between about 1 and about 3 mm for the glassreinforced polymer composite layer 30 and between about 1 and about 6 mmfor the glass layers 32. The glass layers 32 can be any suitable glass,with plate glass, heat strengthened glass or tempered glass beingexamples. The glass layers may be in the form of substantially planarsheets, or in other forms.

It will be appreciated that although methods for making a two-layer anda three-layer laminate have been discussed, other methods of theinvention will result in laminates with more than three layers. Morelayers may result in enhanced strength and impact resistance, forexample. Methods of the invention, for example, may include additionalsteps of binding a glass reinforced polymer composite layer 30 onto oneof the glass layers 32 of FIG. 3, binding an additional glass reinforcedpolymer layer 32 onto the new composite layer 30, and so on to result ina multi-layer composite having desired strength and/or other qualities.FIG. 4 is a schematic cross section of such a laminate. As illustrated,the layers may be of varying thicknesses. Also, it will be appreciatedthat the glass reinforced polymer composite layer 30 may comprise aplurality of individual composites bonded together.

Laminates made through methods of the invention and laminates of theinvention, with those illustrated in FIGS. 3 and 4 being examples, arebelieved to provide substantial strength in combination with atransparency and appearance that is generally consistent with that ofglass. Methods of the invention that result in these and similarlaminates are therefore believed to provide important benefits andadvantages that will be valuable in applications that include vehicleand building windows in addition to many others.

In order to further describe exemplary embodiments of the invention,description of an experimental method and laminate of the invention isprovided. A 2.5 mm transparent glass reinforced polymer composite wasprepared according to a method consistent with that described in FIG. 1above using a polyester precursor solution. It had a glass fiber volumefraction of about 18%, an elastic modulus of about 6.7 Gpa, and shearmodulus of about 1.15 GPa.

Glass layers were then bonded to opposing surfaces of the glassreinforced polymer composite according to the steps of FIG. 2. The glasslayers were between about 3 and about 6 mm thick. A thin layer ofpolyester resin was applied to each of the two surfaces of thetransparent glass reinforced polymer composite, which was thensandwiched between the two glass layers under a nominal pressure. Thesystem cured into an integrated laminated panel after 24 hours. Theresultant laminate was highly impact resistant and could withstand, forexample, the impact of debris during high speed wind storms such ashurricanes. The resultant laminate also showed clarity comparable toglass.

To estimate its impact resistance, the following impact tests wereperformed on 450 mm×300 mm×9 mm laminated composite glass panelssections of the experimental laminate clamped on all four sides betweensilicone rubber glazing:

Impact Number of Impactor type velocity impacts Damage 2 gm sphericalnosed steel 270 mph  25 None 2 gm spherical nosed steel 160 mph  100Shattered front glass layer 100 gm metal impactor with 75 mph 10 Nonewooden front end 100 gm metal impactor with 95 mph 10 None wooden frontend

While specific embodiments of the present invention have been shown anddescribed, it should be understood that other modifications,substitutions and alternatives are apparent to one of ordinary skill inthe art. Such modifications, substitutions and alternatives can be madewithout departing from the spirit and scope of the invention, whichshould be determined from the appended claims. For example, whileexemplary methods of the invention have been described herein asincluding steps in a particular sequence, it will be understood thatmethods of the invention are not be limited to these particularsequences, and that other methods of the invention may be practicesusing the same or similar steps in an alternate sequence. It will alsobe understood that the present invention includes transparent laminatesand composites in addition to methods for making the same, and thatdescription of a method made herein is likewise description of anarticle of the invention that may be made through the method.

Various features of the invention are set forth in the appended claims.

1. A method for making a laminate including at least a glass layer and atransparent composite comprising the steps of: making at least onetransparent glass reinforced polymer composite through steps comprising:combining a refractive index modifier with a polymer precursor solution;combining glass with said precursor solution to result in a glassconcentration of between about 10% and 50% by volume; and, curing saidprecursor solution to create a transparent glass reinforced polymercomposite; and, binding a glass layer to said transparent glassreinforced polymer composite to form the laminate, said glass layerhaving a refractive index substantially equal to the refractive index ofsaid glass with said precursor solution; wherein said transparent glassreinforced polymer composite comprises a first composite layer, andwherein the step of binding comprises applying a binding agent toopposite surfaces of said first composite layer and sandwiching itbetween a plurality of glass layers.
 2. The method of claim 1 whereineach of said plurality of glass layers has a thickness of between about1 and about 6 mm, and wherein said transparent glass reinforced polymercomposite has a thickness of between about 1 and about 3 mm.
 3. Themethod of claim 1 and further including the steps of: making additionalglass reinforced polymer composite layers; binding at least one of saidadditional glass reinforced polymer composite layer to one of saidplurality of glass layers; and, binding an additional glass layer onsaid at least one additional glass reinforced polymer composite layerwherein the resulting laminate includes a plurality of said glassreinforced polymer composite layers alternately stacked with a pluralityof said glass layers.
 4. A method for making a laminate including atleast a glass layer and a transparent composite comprising the steps of:making at least one transparent glass reinforced polymer compositethrough steps comprising: combining a refractive index modifier with apolymer precursor solution; combining glass with said precursor solutionto result in a glass concentration of between about 10% and 50% byvolume; and, curing said precursor solution to create a transparentglass reinforced polymer composite; and, binding a glass layer to saidtransparent glass reinforced polymer composite to form the laminate,said glass layer having a refractive index substantially equal to therefractive index of said glass with said precursor solution; whereinsaid transparent glass reinforced polymer composite comprises a firstcomposite layer, and wherein the step of binding a glass layer to saidfirst composite layer comprises applying a binding agent on said firstcomposite layer to bind said glass layer to said first composite layerat room temperature and pressure.
 5. A method for making a laminateincluding at least a glass layer and a transparent composite comprisingthe steps of: making at least one transparent glass reinforced polymercomposite through steps comprising: combining a refractive indexmodifier with a polymer precursor solution; combining glass with saidprecursor solution to result in a glass concentration of between about10% and 50% by volume; and, curing said precursor solution to create atransparent glass reinforced polymer composite; and binding a glasslayer to said transparent glass reinforced polymer composite to form thelaminate, said glass layer having a refractive index substantially equalto the refractive index of said glass with said precursor solution;wherein said refractive index modifier comprises nanoparticles having arefractive index that is less than that of said precursor solutionwhereby the refractive index of the precursor solution is loweredthrough addition of said nanoparticles.
 6. A method for making alaminate including at least a glass layer and a transparent compositecomprising the steps of: making at least one transparent glassreinforced polymer composite through steps comprising: combining arefractive index modifier with a polymer precursor solution; combiningglass with said precursor solution to result in a glass concentration ofbetween about 10% and 50% by volume; and curing said precursor solutionto create a transparent glass reinforced polymer composite; and, bindinga glass layer to said transparent glass reinforced polymer composite toform the laminate, said glass layer having a refractive indexsubstantially equal to the refractive index of said glass with saidprecursor solution; wherein said refractive index modifier comprisesnanoparticles having a diameter that is between about 100 nm and about200 nm.
 7. A method for making a laminate including at least a glasslayer and a transparent composite comprising the steps of: making atleast one transparent glass reinforced polymer composite through stepscomprising: combining a refractive index modifier with a polymerprecursor solution; combining glass with said precursor solution toresult in a glass concentration of between about 10% and 50% by volume;and, curing said precursor solution to create a transparent glassreinforced polymer composite; and, binding a glass layer to saidtransparent glass reinforced polymer composite to form the laminate,said glass layer having a refractive index substantially equal to therefractive index of said glass with said precursor solution; whereinsaid refractive index modifier comprises ceramic nanoparticles.
 8. Amethod for making a laminate including at least a glass layer and atransparent composite comprising the steps of: making at least onetransparent glass reinforced polymer composite through steps comprising:combining a refractive index modifier with a polymer precursor solution;combining glass with said precursor solution to result in a glassconcentration of between about 10% and 50% by volume; and, curing saidprecursor solution to create a transparent glass reinforced polymercomposite; and, binding a glass layer to said transparent glassreinforced polymer composite to form the laminate, said glass layerhaving a refractive index substantially equal to the refractive index ofsaid glass with said precursor solution; wherein said refractive indexmodifier comprises ceramic nanoparticles having a diameter of betweenabout 50 nm and about 200 nm, and having a refractive index that is lessthan that of said precursor solution whereby the refractive index of theprecursor solution is lowered through addition of said nanoparticles.